1. Field of Invention
The present invention relates to draft sills for use on railway freight cars. More particularly, the present invention relates to a common draft sill that can accommodate both Type E and Type F draft gears.
2. Description of Related Art
In a typical railway freight train, such as that shown in FIG. 1, railway cars 12, 14 are connected end to end by couplers 16, 18. Couplers 16, 18 are each received in draft sills 20, 22 of each respective car along with hydraulic cushioning or other shock-absorbing assemblies (unshown). Draft sills 20, 22 are provided at the ends of the railway car's center sill, and include center plates that rest in center plate bowls of railway car trucks 26, 28.
As shown in FIG. 2, each typical car truck 26 includes a pair of side frames 30, 32 supported on wheel sets 34, 36. A hollow bolster 38 extends between and is supported on springs 40 mounted on the side frames. A bolster center plate bowl 24 is provided having a central opening 42. The bolster center plate bowl 24 receives and supports a circular center plate of the draft sill 20.
FIG. 3 shows a typical cast draft sill mounted to the structure of a railroad freight car 12. In the mounted position, the cast draft sill 20 is secured to an end sill 44, the body bolster 38, and a center sill 46. The draft sill 20 typically has a top wall that is welded or otherwise affixed to a shear plate that is connected to the bottom of the railway car. The railway car center sill 46 typically runs the length of the car (but on some cars may extend around the periphery of the car depending on car configuration). Buff and draft forces are thus generally transferred between the draft sill structure, the car truck and the center sill of the car. The shown draft sill 20 has a draft gear mounted within a draft gear pocket and coupler 16 has its shank extend through the coupler shank opening at the outboard end thereof. A center filler plate 48 is mounted in the center filler plate pocket of the cast draft sill, such as by welding, or may be integrally formed. Center filler plate 48 is receivable within car body center plate 24. A sole plate 50 connects the body bolster 38 over the cast draft sill 20. The draft gear pocket has a pair of draft gear carrier members 52 mounted transversely thereto below draft gear cushioning unit 54. The draft gear carrier members 52 are connected to bottom flanges 56 of the draft sill. The end of the illustrated cast draft sill includes a fish-tail piece 58 that has a generally U-shaped opening 60. The fish-tail plate has a pair of facing horizontally disposed fillets that function to transmit and distribute forces from the draft sill 20 to sides of center sill 46 when the fillet plates and lip are welded to the railroad car center sill.
Currently, a draft sill (either cast or fabricated) is unique to the type of draft gear and coupler being used. There have evolved two primary types: Type E and Type F draft sills that accommodate either an E shank coupler or a F shank coupler. Exemplary known Type E draft sills are shown in FIGS. 4–6 while exemplary known Type F draft sills are shown in FIGS. 7–9. Additional details of standard draft sill casting processes and specifications can be found in, for example, ASF-Keysone's Draft Sill End Casting Finishing Standards (Revised Oct. 30, 1998) found at www.asfusa.com/finisill.htm, the subject matter of which is incorporated by reference herein in its entirety.
The Type E draft sill may include center plate flange holes 62. Both Type E and Type F sills include a draft gear pocket 64 that receives a Type E or Type F draft gear assembly. Both types also may include various front draft lugs 66, rear draft lugs 68, flanges 70, king pin holes 72, king pin relief holes 74, lightener holes 76, safety plate flange holes 78, and shear plate surfaces 80. Some typical cast sills may also include side wall pads 82 or side wall “wings” or webs 84 depending on carbuilder requirements. Further, both types typically include a sill attachment telescoping surface 86, a striker face 88, an optional striker pad 90, and yoke support plate flange holes 92.
There are, however, many major differences between the two types. The front ends of both types are substantially different. Type F draft sills have a deep carrier basket 94 that receives a spring-biased carrier basket coupler support system that may or may not include wear plates 96. The spring-biased support allows limited vertical movement of the Type F coupler assembly. Type F draft sills also include retainer block mounting holes 100. Type E draft sills have no such spring-biased carrier basket system and instead have a fixed horizontal support surface forming a fixed coupler carrier 98 that supports a Type E coupler without vertical movement. The support surface will either have metallic or non-metallic wear plates applied. As such, the end profile looks more rectangular, without the downward extending basket. Type F draft sills also include a top yoke filler plate 102, top yoke filler plate weld holes 104, and yoke head support plate flange holes 106 that are not found on type E draft sills. Besides differences in support, the two types of draft sills also have entirely different coupler attachment mechanisms. For example, Type E draft sills have a cross-key connection 108 that mates horizontally within horizontal keyslot 110 to retain a Type E coupler. On the contrary, Type F draft sills rely on a vertical pin connector 112 to retain a type F coupler.
Each type of draft sill has evolved to adapt to and couple a particular draft gear coupler system, which is configured and suited to differing applications. For example, a Type E draft gear is typically used in short overhang railway cars such as 50′ boxcars, intermodal well cars, covered hopper cars and bottom dump coal cars. A Type F draft gear is typically used in longer overhang railway cars such as 89′ flat cars, centerbeam cars and large covered hopper cars. An additional, more expensive, form of Type F draft gear includes a rotary element in place of the standard draft gear yoke and follower that is free to rotate, allowing rotation of the draft sill relative to the draft coupler gear. This particular application is typically used in rotary dump coal cars in which the coal car is unloaded via the top by rotation of the coal car using the rotary element.